The present inventions relate to sand-control apparatus for use in subterranean wells, and in particular contemplate improved configurations for radially expandable sand-control screen jacket apparatus and methods of using the same.
The control of the movement of sand and gravel into a well bore has been the subject of much importance in the oil production industry. The introduction of sand or gravel into the well bore commonly occurs under certain well conditions. The introduction of these materials into the well commonly causes problems including plugged formations or well tubing, and erosion of tubing and equipment. There have therefore been numerous attempts to prevent the introduction of sand and gravel into the production stream.
A common method to prevent the introduction of sand and gravel into the production stream has been a procedure known as gravel packing. In general, this involves placing selected sand or gravel into the annular space between the well bore and a base pipe introduced into the wellbore for that purpose. The base pipe contains perforations designed to allow well fluids to flow into the base pipe while excluding other material. A sand-control screen is commonly used in conjunction with a base pipe. An appropriately sized screen is commonly formed into a jacket and placed concentrically around the outside of the base pipe to prevent the entry of sand into the base pipe. Exemplary apparatus and methods of attaching a sand-control screen jacket to a base pipe are disclosed in U.S. Pat. No. 5,931,232, and in application Ser. No. 09/602,387, which are both assigned to this assignee and is incorporated herein for all purposes by this reference thereto.
One method of enhancing production in a well using a sand-control screen jacket includes causing the radial expansion of the base pipe and surrounding screen jacket by forcing a mechanical expansion tool through the base pipe. Examples of deformable well screens are disclosed in U.S. Pat. Nos. 5,901,789 and 6,012,522, to Donnelly. These methods use screens and methods to control the screen mesh opening size.
It is important that an expandable sand-control screen maintain its integrity throughout its entire length. Any voids in the screen that permit the entry of sand generally lead to erosion, which in turn allows the entry of more sand into the production stream. Wellbores with irregular sides or a particularly tortuous path, in order to allow sufficient clearance for insertion, generally require sand-control screen jackets having a diameter much smaller than the diameter of the wellbore. The radial expansion of a small diameter sand-control screen jacket into a much larger diameter wellbore can be particularly problematic. Extreme levels of expansion can lead to loss of integrity of the screen jacket connections with the base pipe. The result is the introduction of sand into the production stream and all of the attendant problems associated therewith.
Due to the aforementioned problems with the introduction of sand and gravel into the production stream, a need exists for apparatus and methods ensuring a radially expandable sand-control screen capable of withstanding a high degree of expansion while retaining sand-controlling connections with the base pipe.
The invention provides apparatus and related methods for constructing and using a radially expandable sand-control screen jacket assembly for use in a subterranean well. The screen-jacket assembly has at least two overlapping screen elements surrounding a base pipe, with a longitudinal sand-control seal between screen elements. The assembly maintains sand control after being radially expanded.
According to different aspects of the invention, the screen jacket assembly has two, three, four, or more overlapping screen elements.
According to another aspect of the invention, the assembly is encased in a screen shroud.
According to still another aspect of the invention, the inner screen element edges and outer screen element edges are substantially helical with respect to the to axis of the base pipe.
According to another aspect of the invention, the outer screen element is biased toward the inner screen element.